Heat Exhaustion vs. Heat Stroke

Spot the Signs Before It’s Too Late

So what is the difference between heat exhaustion and heat stroke?

Heat exhaustion and heat stroke are both heat-related illnesses, but they differ significantly in severity and symptoms. 

Heat exhaustion

• Cause: Occurs when the body loses excessive water and salt through sweating, typically due to exertion in a hot environment.
• Symptoms: Includes headache, dizziness, nausea, weakness, heavy sweating, muscle cramps, and cool, pale, or clammy skin.
• Body Temperature: The core body temperature is elevated but remains below 104°F (40°C).
• Mental Status: Generally, mental status remains normal, although the person might feel momentarily dizzy or confused.
• Treatment: Can often be treated by moving to a cooler area, loosening clothing, drinking cool fluids (water or sports drinks), and applying cool, wet cloths to the skin.
• Progression: If left untreated, heat exhaustion can escalate to heat stroke. 

Heat stroke

• Cause: A serious medical emergency where the body’s cooling system fails completely, leading to a dangerous rise in body temperature.
• Symptoms: The most significant distinction is a change in mental status, which can include confusion, slurred speech, seizures, loss of consciousness, or even coma. Other symptoms include very high body temperature (above 104°F), hot, dry skin (though sweating may be present in exertional heat stroke), rapid pulse and breathing, nausea, and vomiting.
• Body Temperature: The core body temperature rises above 104°F (40°C).
• Mental Status: Marked by persistent neurological dysfunction, such as confusion, disorientation, seizures, and loss of consciousness.
• Treatment: Requires immediate medical attention (call 911 or emergency services). While waiting for help, cool the person rapidly using methods like external application of cool water to the skin, applying ice packs, or using evaporation techniques. Do not give fluids.
• Severity: A life-threatening condition that can result in organ damage, permanent disability, or death if not treated promptly. 

Key differences at a glance

Feature	Heat Exhaustion	Heat Stroke
Severity	Serious, but typically not life-threatening if treated	Life-threatening medical emergency
Body Temperature	Elevated, but below 104°F (40°C)	Above 104°F (40°C)
Sweating	Heavy sweating	Decreased or no sweating (can still be moist in exertional heat stroke)
Skin	Cool, pale, or clammy	Hot and dry (can still be moist in exertional heat stroke)
Mental Status	Generally normal, may be briefly dizzy or confused	Confusion, disorientation, seizures, loss of consciousness
Treatment	Move to cool area, rest, hydrate, cool skin	Call 911, cool body rapidly (e.g., cold water immersion), do not give fluids

In summary, heat exhaustion is a serious condition that can be managed with self-care and attention, but it can progress to heat stroke if untreated. Heat stroke is a medical emergency requiring immediate attention and aggressive cooling measures to prevent severe consequences.

We strongly advise that first aid kits include a portable body thermometer and that crews in the field make liberal use of this tool when there is any doubt about a crewperson’s body heat status.  The earlier a condition is observed the better to engage in a treatment option.

Stay safe. Stay cool. It’s not worth getting all heated up.